Alan Turing - Computer Scientist

He was born into a solidly upper middle class English family on 23 June, 1912. His talent for mathematics and his disinterest in any other subject came to light soon after he started Sherbourne School. Here he also formed a close and intense relationship with a fellow pupil, Christopher Morcom, who was similarly interested in mathematics and science. Morcom's early death from tuberculosis had a profound effect on Turing and his scepticism about religion quickly converted to full-blown atheism.

The Turing Machine

Turing went up to King's College, Cambridge in 1931. Four years later he was elected a fellow and the following year published a paper detailing what later became known as the Turing Machine. Developed in an attempt to clearly and precisely define algorithms, it performed tasks by reading a series of instructions contained in binary code on a length of tape. In effect, it was a basic computer program.

Enigma

Turing completed his PhD at Princeton University as war broke out in 1939, and he was recruited by the British cryptanalytic department to work on deciphering the Nazi Enigma and Lorenz ciphers. Bletchley Park was home to an eclectic mix of mathematicians, chess players, archaeologists and society girls who worked together in an attempt to crack what was popularly believed to be an unbreakable code.

Turing's answer was what we would recognise as a crude computer, called the Bombe1. Aided by the capture of Enigma code books from the stricken submarine U-559 in 1943 , the Allies were at last able to decipher at high speed the coded messages sent between the German High Command and U-boats in the Atlantic Ocean. Contrary to Hollywood cinema, the first Nazi enigma machines and codebooks were captured by the British Navy.

MADAM and the Turing Test

After 1945, Turing returned to academia where he was to publish various papers on what he termed as 'thinking machines', or artificial intelligence. After spells at Cambridge University and the Nation Physical Laboratory, he took up a post with Manchester University where he had the opportunity to build a real Turing Machine. The result was the Manchester Automatic Digital Machine (MADAM). Turing was responsible for the algorithms, programs and operating manual for MADAM and he was able to utilise it to continue his research. During this time he continued to work for British Military Intelligence.

In 1950 he published the landmark paper entitled Computer Machinery and Artificial Intelligence, in which he asked 'Can computers think?'. This formed the basis of the Turing Test. The test rests on the assertion that computers can only be considered intelligent when their conversational ability makes it impossible for them to be distinguished from a human being. In honour of his achievements, Turing was made a Fellow of the Royal Society in 1951.

Turing's Final Years

In 1952 Alan Turing was arrested and convicted of gross indecency after he confessed to having had an homosexual affair with someone implicated in a robbery at Turing's home2. Unable to face a term in prison, he agreed to a course of female hormones, which it was believed would 'control his lust'. Turing was disgusted by the resulting changes in his body and despaired at the fact that he was under constant guard, having been privy to state secrets. On 7 June, 1954, he ate an apple that he had laced with cyanide. The coroner's report recorded the cause of death as 'self-administered potassium cyanide while in a moment of mental imbalance'.

1At the time of writing, the Enigma decoding machines are prominent in the British Press. One of the machines was stolen from Bletchley Park Museum. The story, catalogued on their website, has more twists and plots than your average spy novel.2Homosexuality was illegal in England and Wales until 1967.

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